Variable nozzle turbocharger... what's one of them then?

[Mike B]

Out at the Toyota Dealership today getting track rod ends for the old girl and happened to pick up a brochure for the new Rav 4 for the family. The most powerful engine is the new diesel - 4 cyl, 2.2, 177 brake, 400nm trq.

It's on boost according to the dyno at 1.5k, using a variable nozzle turbo charger.... -I know it's a diesel, and it only revs to 3 and a bit, but what's a variable nozzle turbo?

I have an idea.... to do with creating boost earlier??

[paul mac]

i think i read these are most suited to low power instalations and as you say avoid lag, i think its to do with the blades of the turbo being at the right angle for the gas flow, I'me sure a smart arse will be along shortly whos spent 2 hours doing a google search lol

[Gamer]

Variable geometry turbocharger improves upon turbocharger design by automatically changing the size of the vanes in the turbine housing, allowing control of boost by controlling exhaust turbine inlet pressure. The size of vanes changes positively as engine speed increases. At low engine speeds, the increased pressure generates higher boost than traditional turbine design.

Holset variable geometry turbocharger changes exhaust air pressure by using piston to push vanes parallel to the rotational axis, instead of pivoting the vanes.

http://en.wikipedia.org/wiki/Variable_geometry_turbocharger


;)

[Gamer]

I'me sure a smart arse will be along shortly whos spent 2 hours doing a google search lol


More like 2 minutes.. ;)

[Mike B]

OK, I thought it was this...

so why don't we see this tech on big singles- if you can get more low end power from a big single that would be the holy grail, right?

[Gamer]

Just guessing here but I would think cost and the fact that it is such a new technology that it has not caught on yet. There could also be other factors like this tech can only be used in smaller turbos for the moment.

I don't really know though and am just taking a wild stab at it really.

More reading here:

http://www.holset.co.uk/files/2_5_1_5-variable%20geometry.php

[D3xt3r]

Diesel engines are not as hot as gasoline engines. The hot exhaust gases of the gas engines brake the mechanism pretty fast so it isnt used in normal engines.

The new Porsche Turbo uses two variable KKK Turbos but those are with some space age material whatever so really expensive I suppose.

[Alex]

Yep the new 997 911 Turbo is the first petrol powered car to run them.

Now that the technology has been sorted for OEM use you'll see aftermarket options arrive in the future.

[Mike B]

That is something I would be seriously interested in, but I bet it would take quite a bit of additional setting up...

Looking forward to seeing the aftermarket versions and some dyno plots! - if it works well it must be one of the biggest developments for the big single community...

[Ian C]

It wouldn't take that much more setting up / controlling. You could run one of these suckers off a E-Manage Ultimate if it's solenoid duty controlled, and it probably is, variable positioning via an oil pressure system. Even easier if it's two step, but I imagine the technology will bypass two step almost instantly.

I'd love to have a go with one but they are some years off the aftermarket yet. Premium cars first, a la Porsche, then mass produced small turbos for downsizing engines rather than making existing ones more powerful. Then riotously expensive aftermarket stuff :D

-Ian

[paul mac]

I'd love to have a go with one but they are some years off the aftermarket yet. Premium cars first, a la Porsche, then mass produced small turbos for downsizing engines rather than making existing ones more powerful. Then riotously expensive aftermarket stuff :D

-Ian
do agree with you here Ian technology always trickles down from the top, i think the problem is the mass producers have really turned there back on turbos in the GT type of class we are in prefering to up the capacity instead, lets be honest porsche variable vane turbos will be a very small niche market, so without this real mass produced research and development from ford, nissan, toyota etc i think the trickle down will take a long long time:(

[Ian C]

Well, what you do get is this "engine downsizing" where new technology is used not to make existing engines more powerful, but to keep the engine's power the same while making it smaller. So a boggo NA 2.0 litre family saloon engine could spit out 120bhp a few years ago, now a 1.4 with intake and exhaust VVTi, direct injection, modern oil and production tolerances etc etc can make the same if not more power, using less fuel and burning cleaner.

If you bung a variable nozzle, or even better a variable *vane* turbo (which is what the Porsche system is) onto a 1.4 engine like that you could push over 100bhp/ton in a production engine while still having the 1.4 off-boost drivability and economy and cleanliness and also have no lag to speak of.

Once that's perfected, the looney tunes brigade will start retrofitting it to T67's ;)

-Ian

[paul mac]

Once that's perfected, the looney tunes brigade will start retrofitting it to T67's ;)
-Ian
i presume thats the exact moment us lot fit in lol:D